Content distribution over the Internet is rapidly increasing. One area of considerable growth is video-on-demand over the Internet. However, providing high-quality Internet video-on-demand with a traditional client-server model is very costly. More importantly, the ever-mounting demand is adding significant pressure onto existing server-based infrastructures (such as data centers, content distribution networks (CDNs)), which are already under heavy burden to live up to their current load. As a result, high-profile failures are not uncommon.
Fortunately, on the heel of such crisis, peer-to-peer (P2P) networks come to rescue. Indeed, Internet video streaming (both on-demand and live broadcast) using various peer-to-peer or peer-assisted frameworks has been shown to greatly reduce the dependence on infrastructure servers, as well as bypass bottlenecks between content providers and consumers. Content distribution using a P2P network greatly reduces dependence on infrastructure servers and scales up to the demand of the Internet video era. However, it has also fundamentally altered the relationship among content owners, Internet service providers (ISPs), and consumers. In particular, ISPs on one hand are spending billions to maintain and upgrade their networks in order to support the ever increasing traffic due largely to P2P. On the other hand, ISPs are also being marginalized by content owners' direct reaching to consumers. As a result, unhappy ISPs started to put up various hurdles for P2P applications (such as throttling P2P traffic or even taking active measures to deter P2P traffic). These practices, however, created a huge backlash once they were discovered and made public. ISPs now realize that it is in their best interest to work collaboratively with content providers and consumers. However, to provide to ISPs to embrace P2P networks, any solution has to include a way for P2P applications to become ISP-friendly at the protocol level.
In general, ISP-unfriendly traffic refers to all levels of traffic unfriendly to ISPS. It includes traffic crossing ISP boundaries, between post-office protocols (PoPs), or even among different neighborhoods within the same ISP and PoP. Crossing ISP boundary traffic is a particularly significant concern of all the ISP-unfriendly traffic. ISP-unfriendly traffic is detrimental to ISPs because it increases an ISP's cost of doing business. This increase in the cost of doing business for the ISP is passed on to the user in the form of higher prices to access the Internet. This makes users unhappy. Thus, it is a double-edged sword for the ISP, who wants to keep prices low to attract customers but faces users wanting to exchange content using P2P content distribution.
At least two broad types of techniques have been used in an attempt to make P2P application more ISP-friendly. The aim of these techniques is to ensure quality of service (QoS) to an end user, to try and use as much of the P2P resources as possible, and to minimize adverse impact to the ISP.
One type of technique addresses the network topology of the P2P network. These topology-based techniques include biased neighbor selection and can be extended to take into account multi-tier network topology, from subnets, POPs, to ISPs. The topology building mechanism can also be implicit. Another type of techniques uses rate allocation to improve ISP-friendliness. Current rate allocation techniques apply a distributed optimization framework to P2P networks. However, each of these rate allocation techniques focuses on either application layer multicast or P2P live streaming.